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1.
Ecotoxicol Environ Saf ; 193: 110341, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32092582

RESUMO

An in-situ experiment was performed to study metabolic responses of the freshwater mussel Diplodon chilensis to water contaminated by leachates from an open dump and cattle activity, in order to analyze both the effects of those contaminants on aquatic environments and the potential use of a native bivalve to evaluate the effects of anthropic influence and eutrophication. Bivalves from a reference site were cage-transplanted to a control site (site A) and to a temporal water pond (site B) over 30 and 60 periods. Water quality analyses revealed that the site B was affected by anthropogenic influence. Mussel's hemocytes from site B showed 50% lower reactive oxygen species production and 130% higher lysosomal membrane stability in the site B mussels. In addition, no oxidative stress was evident in gills, despite the elevated copper and iron concentrations recorded in the site B water samples (CuB = 0.3350 ± 0.0636 mg. L-1vs. CuA = 0.0045 ± 0.0007 mg. L-1; FeB = 3.8650 ± 0.4031 mg. L-1vs. FeA = 0.0365 ± 0.0049 mg. L-1). In contrast, the adductor muscle accumulated more Fe (~10-20-fold) than the gills and showed signs of oxidative stress, e.g. superoxide dismutase activity and TBARS levels were increased by 10% were 34%, respectively, in the site B compared with the site A after 60 days of exposure. Additionally, the adductor muscle showed signs of anaerobic metabolism activation. Cu is accumulated in gills from both sites' individuals, at 60 days, in concordance with the increase in the activity of the cu-containing enzyme cytochrome-c-oxidase. There was a reduction in the overall condition and digestive gland index in bivalves exposed at site B, associated with diminished levels of lipid and protein contents. Metal-pollution and eutrophication affects D. chilensis metabolism and is associated to tissue-specific exposure, anaerobic metabolism and general energetic condition depletion.


Assuntos
Bivalves/efeitos dos fármacos , Eutrofização , Metais Pesados/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Bivalves/enzimologia , Bivalves/metabolismo , Bovinos , Cobre/metabolismo , Água Doce , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Hemócitos/efeitos dos fármacos , Hemócitos/metabolismo , Metais Pesados/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Poluentes Químicos da Água/metabolismo , Qualidade da Água
2.
Anaesthesia ; 73(11): 1345-1352, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30168596

RESUMO

Optimal positioning for anaesthesia in pregnant women involves balancing the need for ideal tracheal intubation conditions (achieved by the head elevated ramped position), with the prevention of reduced cardiac output from aortocaval compression (achieved by left lateral pelvic tilt). No studies have examined the effect on cardiac output of left lateral pelvic tilt in the ramped position. We studied non-labouring, non-anaesthetised healthy term pregnant women who underwent baseline (left lateral decubitus) cardiac assessment using transthoracic echocardiography. We then compared cardiac output, maternal physiological variables, fetal heart rate and comfort scores in three positions: left lateral decubitus; ramped position with wedge; and ramped position alone. Thirty women completed the study. Mean (SD) age, gestation and body mass index were 33.5 (3.93) years, 38.5 (0.94) weeks and 29.0 (4.0) kg.m-2 , respectively. Mean ejection fraction, left ventricular internal diameter and mitral valve E/e' were 55.2 (6.8) %, 4.70 (0.43) cm and 7.50 (1.82), respectively. There were no differences in cardiac output between the positions (p = 0.503). There were no differences in systolic (p = 0.955) or diastolic (p = 0.987) blood pressure, maternal heart rate (p = 0.133), oxygen saturation, respiratory rate (p = 0.964) or fetal heart rate (p = 0.361) between ramped with wedge and ramped alone positions. Left lateral decubitus was most comfortable (p = 0.001), however, there were no differences in comfort levels between ramped with wedge and ramped alone positions. The ramped position without left lateral tilt is safe and acceptable in non-labouring, non-anaesthetised, healthy term pregnant women. Left lateral pelvic tilt may be unnecessary in the head elevated ramped position in term pregnant women.


Assuntos
Ecocardiografia , Hemodinâmica/fisiologia , Posicionamento do Paciente/métodos , Postura/fisiologia , Adulto , Débito Cardíaco/fisiologia , Feminino , Frequência Cardíaca Fetal/fisiologia , Humanos , Satisfação do Paciente/estatística & dados numéricos , Gravidez , Terceiro Trimestre da Gravidez , Estudos Prospectivos , Descanso
3.
Parasite Immunol ; 39(11)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28857186

RESUMO

NTPDases are enzymes that hydrolyse diphosphate and triphosphate nucleosides, regulating purinergic signalling in many organisms. The Schistosoma mansoni NTPDases, SmATPDases 1 and 2, are antigenic proteins and display a significant homology with the isoforms found in mammalian cells. In this work, we investigated whether anti-SmATPDase antibodies from S. mansoni-infected mice sera show cross-reactivity with the NTPDase 1 isoform from macrophages and how this event affects the cell proliferation. By Western blot, anti-SmATPDase antibodies present in serum from infected mice recognized 2 bands with approximately 53 and 58 kDa, corresponding to NTPDase 1. Additionally, the enzyme was identified in macrophages by immunofluorescence and the anti-SmATPDase antibodies were able to reduce activity enzyme (22%). Macrophages incubated with commercial polyclonal antibodies reactive with NTPDase 1 (anti-CD39) showed a reduction of 40% of the enzyme activity. In proliferation assays, macrophage proliferation was inhibited 11% and 90% by pooled sera from infected animals and anti-CD39, respectively. The results suggest that inhibition of NTPDase 1 in macrophages by antibodies produced against the isoforms of the S. mansoni ATPDases could be a mechanism of regulation in the immune response during experimental schistosomiasis.


Assuntos
Anticorpos Antiprotozoários/imunologia , Antígenos CD/imunologia , Antígenos de Protozoários/imunologia , Apirase/imunologia , Reações Cruzadas/imunologia , Macrófagos/imunologia , Schistosoma mansoni/imunologia , Esquistossomose/imunologia , Animais , Anticorpos Antiprotozoários/sangue , Western Blotting , Linhagem Celular , Proliferação de Células/fisiologia , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Células RAW 264.7 , Esquistossomose/parasitologia , Caramujos/parasitologia
4.
Pediatr Cardiol ; 38(4): 840-852, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28289784

RESUMO

The aims of the study were to determine (1) whether the presence of High blood pressure (HBP) states in the youth associate a steeper rate of age-related change in arterial geometrical and wall properties with respect to subjects with no previous cardiovascular risk factor (CRF) exposure, (2) in which parameters and in what magnitude, and (3) the existence of a gender-related difference in the impact of this condition on arterial properties. 300 individuals (mean/range: 15/4-29 years; 133 females) were included. Two groups were assembled: (1) Reference: nonprevious exposure to traditional CRF and (2) HBP: subjects with arterial hypertension and/or elevated blood pressure (BP) levels during the study. Additionally, HBP subjects were separated in BP-related subgroups. Measured parameters were (1) central (aortic) arterial BP and aortic pulse wave analysis parameters, (2) carotid and femoral artery local (pressure-strain elastic modulus) and regional (pulse wave velocity; PWV) stiffness, and (3) arterial diameters and carotid intima-media thickness (CIMT). Age-related changes in these parameters (absolute values and z-scores) were explored by obtaining simple linear regression models for each group. HBP presented a steeper rate of change (accelerated vascular aging; VA) for most of the parameters assessed, mainly in central (aortic) hemodynamics. VA increased as the HBP level got higher. Both males' and females' aging rates were affected by this condition, but females presented a more marked relative age-related increase with HBP exposure. HBP states in the youth gradually associate accelerated VA, with a progressive hemodynamic-structural-functional onset of damage, with females presenting a more marked relative HBP-associated arterial repercussion.


Assuntos
Envelhecimento , Artérias/fisiopatologia , Hipertensão/fisiopatologia , Doenças Vasculares/fisiopatologia , Adolescente , Adulto , Aorta/fisiopatologia , Pressão Arterial , Artérias Carótidas/fisiopatologia , Espessura Intima-Media Carotídea , Criança , Pré-Escolar , Feminino , Artéria Femoral/fisiopatologia , Hemodinâmica , Humanos , Masculino , Análise de Onda de Pulso , Fluxo Sanguíneo Regional , Fatores de Risco , Fatores Sexuais , Rigidez Vascular , Adulto Jovem
5.
Anaesthesia ; 70(9): 1028-38, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25891669

RESUMO

Haemodynamic and cardiac structural changes in severe pre-eclampsia and in pregnant women with human immunodeficiency virus (HIV) infection have not been clearly established. We performed transthoracic echocardiography on 105 women. Women with pre-eclampsia demonstrated (mean (SD), untreated vs treated) preserved fractional shortening (40 (7.1)% vs. 41 (8.6)%), a non-dilated left ventricle (4.5 (0.49) cm vs. 4.4 (0.44) cm), increased mitral valve E/septal e' (10.5 (3.3) vs. 10.6 (2.8)), and preserved tricuspid annular plane systolic exertion (2.6 (0.36) cm vs. 2.4 (0.51) cm). Women with HIV infection demonstrated (mean (SD), HIV-positive vs healthy) a reduced cardiac index (2.8 (0.64) ml.min(-1) .m(-2) vs. 3.1 (0.7) ml.min(-1) .m(-2) , p = 0.029), reduced septal s' tissue Doppler velocity (8.5 (1.5) cm.s(-1) vs. 9.3 (1.7) cm.s(-1) , p = 0.042), increased left ventricular end-diastolic area (7.6 (2.1) cm2 vs. 6.3 (1.7) cm2 , p = 0.004), and reduced right ventricular s' and e' velocity (s' velocity 14.7 (3.1) cm.s(-1) vs. 7.0 (2.9) cm.s(-1) p = 0.001, e' velocity 16.3 (4.1) cm.s(-1) vs. 18.7 (3.4) cm.s(-1) , p = 0.013). The mitral value E/septal e' was > 8 in 39% of patients with HIV. Fractional shortening (< 28%) was reduced in 10% of healthy women, and mitral valve E/septal e' ratios were > 8 in 38% of that group. Women with pre-eclampsia demonstrated preserved systolic function, with diastolic dysfunction. Women with HIV demonstrated reduced left and right ventricular systolic function, with increased ventricular dilatation.


Assuntos
Ecocardiografia/métodos , Infecções por HIV/fisiopatologia , Hemodinâmica , Pré-Eclâmpsia/fisiopatologia , Complicações Infecciosas na Gravidez/fisiopatologia , Adulto , Velocidade do Fluxo Sanguíneo , Comorbidade , Feminino , Infecções por HIV/epidemiologia , Ventrículos do Coração/diagnóstico por imagem , Humanos , Pré-Eclâmpsia/epidemiologia , Gravidez , Complicações Infecciosas na Gravidez/epidemiologia , Estudos Prospectivos , África do Sul/epidemiologia , Volume Sistólico
6.
J Helminthol ; 89(4): 465-70, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24725503

RESUMO

Toxocara canis and Toxocara cati are nematode parasites in dogs and cats, respectively, transmitted by ingestion of embryonated eggs, transmammary and transplacental (T. canis) routes and paratenic host predation. Many parasites use mechanisms that change the behaviour of their hosts to ensure continued transmission. Several researchers have demonstrated behavioural changes in mouse models as paratenic hosts for T. canis. However, there have been no studies on behavioural changes in laboratory rats (Rattus norvegicus) experimentally infected with T. cati. This study investigated behavioural changes and muscle strength in male and female rats experimentally infected with T. cati or T. canis in acute and chronic phases of infection. Regardless of sex, rats infected with T. cati showed a greater decrease in muscle strength 42 days post infection compared to rats infected with T. canis. However, behavioural changes were only observed in female rats infected with T. canis.


Assuntos
Comportamento Animal , Força Muscular , Toxocara/fisiologia , Toxocaríase/patologia , Animais , Feminino , Masculino , Ratos
7.
Anaesthesia ; 69(5): 436-44, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24673113

RESUMO

The aim of this study was to investigate cardiac function and haemodynamic indices using transthoracic echocardiography in women with severe pre-eclampsia who had already received treatment interventions. Fifteen women with treated severe pre-eclampsia were studied using transthoracic echocardiography. Mean (SD) cardiac output in women with treated disease was 5690 (1708) ml.min(-1). Systolic function was preserved in women with treated disease evidenced by mean (SD) fractional shortening 41 (9)%, fractional area change 62 (12)% and septal s' velocities 9.0 (2.1) cm.s(-1). Left ventricle end-diastolic diameters were within healthy reference ranges at 4.7 (0.3) cm and the left ventricle was not dilated. Diastolic function was reduced, with a mean (SD) mitral valve E/septal e' ratio of 12.6 (4.1). Left ventricular mass was increased at 182.0 (44.4) g. There was large variability in haemodynamics in women with treated severe pre-eclampsia. Transthoracic echocardiography is acceptable and applicable and enables quantification of cardiac function in women with severe pre-eclampsia.


Assuntos
Ecocardiografia/métodos , Hemodinâmica/fisiologia , Pré-Eclâmpsia/diagnóstico por imagem , Adulto , Débito Cardíaco/fisiologia , Diástole/fisiologia , Feminino , Ventrículos do Coração/diagnóstico por imagem , Humanos , Variações Dependentes do Observador , Pré-Eclâmpsia/terapia , Gravidez , Volume Sistólico/fisiologia , Sístole/fisiologia
8.
Food Microbiol ; 36(2): 481-7, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24010632

RESUMO

The aim of this work was the genetic characterization at the strain level of 39 presumed Geotrichum candidum isolates isolated throughout the artisanal manufacturing and ripening of Armada cheese and tentatively identified at genus and/or species level by phenotypic characteristics. The molecular identification of the strains included among others the amplification and sequencing of the D1/D2 domains of the 26S rRNA gene. A restriction fragment length polymorphism (RFLP) analysis with the ITS1-5.8S-ITS2 PCR amplicons and a randomly amplified polymorphic DNA (RAPD) analysis with five different primers were carried out. The bands pattern profile obtained through RFLP by enzymatic restriction with HinfI was the same for all the strains studied, which confirmed the classification of the strains at species level. A RAPD-PCR analysis with three different primers was applied to assess the intraspecific diversity, in this way 16 band profiles were obtained for the 39 strains studied by the combined use of primers Ari1 and Omt1. This study contributes to know the occurrence and genotypic biodiversity of G. candidum in Armada cheese.


Assuntos
Queijo/microbiologia , Geotrichum/genética , Geotrichum/isolamento & purificação , Leite/microbiologia , Animais , Bovinos , DNA Fúngico/genética , Variação Genética , Geotrichum/classificação , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição
9.
J Hum Evol ; 60(4): 481-91, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20573376

RESUMO

The dispersal of hominins may have been favored by the opening of the landscape during the Early-Middle Pleistocene transition (EMP) in Western Europe. The structure of the small-vertebrate assemblages of the archaeo-paleontological karstic site of Gran Dolina in Atapuerca (Burgos, Spain) shows important environmental and climatic changes in the faunal succession, across the Matuyama-Brunhes boundary at 780 ka. These changes are interpreted to indicate impoverishment of the forests, along with an increase in dry meadows, and open lands in general that entailed a tendency towards the loss of diversity in small-vertebrate communities above the EMP. We evaluate variation in diversity of the faunal succession of Gran Dolina using Shannon's Second Theorem as an index of ecosystem structure. The long cultural-stratigraphic sequence of Gran Dolina during the EMP is somewhat similar in its completeness and continuity to that in the locality of Gesher Benot Ya'aqov in the Upper Jordan Valley. We also evaluate related data including faunal and floral (pollen) succession. Both localities present cold, dry and humid, warm fluctuations at the transition between the Early and the Middle Pleistocene. Comparisons between these sites present opportunities to understand large-scale climatic changes.


Assuntos
Anfíbios/classificação , Evolução Biológica , Mudança Climática , Fósseis , Mamíferos/classificação , Répteis/classificação , Animais , Arqueologia , Emigração e Imigração , Meio Ambiente , Hominidae/fisiologia , Humanos , Paleontologia , Espanha
10.
Science ; 276(5317): 1392-5, 1997 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-9162001

RESUMO

Human fossil remains recovered from the TD6 level (Aurora stratum) of the lower Pleistocene cave site of Gran Dolina, Sierra de Atapuerca, Spain, exhibit a unique combination of cranial, mandibular, and dental traits and are suggested as a new species of Homo-H. antecessor sp. nov. The fully modern midfacial morphology of the fossils antedates other evidence of this feature by about 650, 000 years. The midfacial and subnasal morphology of modern humans may be a retention of a juvenile pattern that was not yet present in H. ergaster. Homo antecessor may represent the last common ancestor for Neandertals and modern humans.


Assuntos
Fósseis , Hominidae , Adulto , Animais , Criança , Dentição , Ossos Faciais , Hominidae/classificação , Humanos , Mandíbula , Crânio , Espanha
11.
Science ; 277(5329): 1086-8, 1997 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-9262474

RESUMO

It has been suggested that European Middle Pleistocene humans, Neandertals, and prehistoric modern humans had a greater sexual dimorphism than modern humans. Analysis of body size variation and cranial capacity variation in the large sample from the Sima de los Huesos site in Spain showed instead that the sexual dimorphism is comparable in Middle Pleistocene and modern populations.


Assuntos
Constituição Corporal , Fósseis , Hominidae/anatomia & histologia , Caracteres Sexuais , Crânio/anatomia & histologia , Animais , Feminino , Humanos , Masculino , Espanha
12.
Science ; 269(5225): 826-30, 1995 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-7638598

RESUMO

Human remains dating to more than 780,000 years ago are associated with a rich faunal and lithic assemblage in the Pleistocene cave site of Gran Dolina (TD), Sierra de Atapuerca, Burgos, Spain. The micromammal species represent the late Biharian (Mimomys savini zone), and the lithic objects represent pre-Acheulean technology (Mode 1) and comes from the TD6 level below the Matuyama-Brunhes boundary. The Gran Dolina hominid fossils cannot be comfortably accommodated in any of the defined Homo species. They could be considered a primitive form of Homo heidelbergensis, but a new species might be named in the future if the sample is enlarged. The new human fossil evidence demonstrates that Western Europe was settled at least since the late early Pleistocene.


Assuntos
Fósseis , Hominidae , Animais , História do Século XX , História Antiga , Hominidae/anatomia & histologia , Hominidae/classificação , Humanos , Paleodontologia , Espanha , Dente/anatomia & histologia
14.
Rev Port Cir Cardiotorac Vasc ; 16(2): 103-7, 2009.
Artigo em Português | MEDLINE | ID: mdl-19823708

RESUMO

The authors report the clinical case of a 29 year-old caucasian male, previously healthy, victim of traffic accident with head and chest trauma, resulting in a prolonged stay (around 60 days) in an intensive care unit. After hospital discharge, the patient noticed a slow growing of a left supraclavicular pulsatile mass, associated with pain, both local and irradiating to the left arm. The diagnostic investigation revealed a complex false aneurysm with associated arterio-venous fistulae, dissecting cervical muscle planes and involving the braquial plexus. He was submitted to surgical intervention consisting in the ligation of a scapular afferent artery and ligation of communication to the internal jugular vein, with significant decrease in the intra-luminal blood flow velocity. He was subsequently submitted to percutaneous eco-guided thrombin injection under Valsalva manouver, with complete thrombosis of the false aneurysm. There was a quick resolution of the clinical complaints and a progressive reduction of the mass volume (6 month follow-up). A discussion is made on the main features of this entity, normally its etiopathogeny, surgical management and false aneurysm exclusion by means of eco-guided injection of thrombin.


Assuntos
Falso Aneurisma , Artéria Subclávia , Adulto , Falso Aneurisma/diagnóstico , Falso Aneurisma/cirurgia , Humanos , Masculino
15.
Rev Port Cir Cardiotorac Vasc ; 16(2): 91-6, 2009.
Artigo em Português | MEDLINE | ID: mdl-19823706

RESUMO

The introduction of endovascular procedures in the routine of vascular surgery allowed for the expansion of therapeutic options in the diverse areas of vascular disease. Endoluminal revascularization can be regarded as a usefull complement of conventional surgical techniques. An above-knee femoro-popliteal bypass surgery ePTFE graft has been performed, followed by a sheath introduction on the graft body. This allows a simplified access to crural vessels, while providing efficient revascularization of the femoro-popliteal sector. Distal revascularization was performed using angioplasty and stenting when appropriate, as to insure continuous flux in at least one of the tibial or the peroneal arteries. The aim of this kind of procedure is to insure efficient femoro-popliteal revascularization and to achieve a run-off to the foot in at least one vessel. This type of intervention may be particularly attractive in Leriche-Fontaine's grade IV patients with no available autologous venous graft.


Assuntos
Isquemia/cirurgia , Perna (Membro)/irrigação sanguínea , Angioplastia , Prótese Vascular , Estado Terminal , Humanos
17.
Int J Obstet Anesth ; 36: 56-65, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30143429

RESUMO

BACKGROUND: Pre-eclampsia is characterised by increased left ventricular wall thickness on transthoracic echocardiography (TTE). This is assumed to be myocardial hypertrophy, however TTE cannot determine myocardial structure which may be muscle, oedema or fibrosis. Given the high incidence of peripheral oedema in pre-eclampsia, we hypothesised that increased thickness could represent oedema. Cardiovascular magnetic resonance (CMR) characterises myocardial tissue, differentiating between hypertrophy, oedema and fibrosis. This pilot study was designed to characterise myocardial composition using CMR in pregnant women (healthy or with pre-eclampsia) and to compare cardiac output and left ventricular mass using TTE and CMR. METHODS: Thirty-six women (31 healthy, five with pre-eclampsia) underwent TTE and CMR and left ventricular mass was assessed applying standard definitions. Myocardial signal intensities were measured from left ventricular segments and compared to serratus anterior muscle to determine global myocardial signal intensity. Myocardial oedema was defined as a myocardial:skeletal signal intensity ratio >1.9. Agreement between devices for cardiac output and left ventricular mass, and inter- and intra-observer measurements used Bland Altman methodology, calculating the agreement tolerable interval: >1.5 is unacceptable, 1.0-1.5 is marginal and <1.0 is acceptable agreement. RESULTS: Myocardial oedema was present in two (40%) pre-eclamptic women but no healthy women (P=0.017). Agreement for cardiac output was acceptable, for left ventricular mass marginal, and for inter- and intra-observer measurements acceptable. CONCLUSIONS: Cardiovascular magnetic resonance was used to characterise the myocardial tissue in women with pre-eclampsia. Data suggest that some women with pre-eclampsia have myocardial oedema rather than hypertrophy.


Assuntos
Edema/diagnóstico por imagem , Edema/patologia , Cardiopatias/diagnóstico por imagem , Cardiopatias/patologia , Imageamento por Ressonância Magnética/métodos , Pré-Eclâmpsia/patologia , Adulto , Austrália , Débito Cardíaco/fisiologia , Edema/complicações , Feminino , Cardiopatias/complicações , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/patologia , Ventrículos do Coração/efeitos da radiação , Humanos , Tamanho do Órgão , Projetos Piloto , Gravidez , Estudos Prospectivos , Reprodutibilidade dos Testes
18.
Sci Rep ; 8(1): 1389, 2018 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-29362499

RESUMO

Electrification in volcanic ash plumes often leads to syn-eruptive lightning discharges. High temperatures in and around lightning plasma channels have the potential to chemically alter, re-melt, and possibly volatilize ash fragments in the eruption cloud. In this study, we experimentally simulate temperature conditions of volcanic lightning in the laboratory, and systematically investigate the effects of rapid melting on the morphology and chemical composition of ash. Samples of different size and composition are ejected towards an artificially generated electrical arc. Post-experiment ash morphologies include fully melted spheres, partially melted particles, agglomerates, and vesiculated particles. High-speed imaging reveals various processes occurring during the short lightning-ash interactions, such as particle melting and rounding, foaming, and explosive particle fragmentation. Chemical analyses of the flash-melted particles reveal considerable bulk loss of Cl, S, P and Na through thermal vaporization. Element distribution patterns suggest convection as a key process of element transport from the interior of the melt droplet to rim where volatiles are lost. Modeling the degree of sodium loss delivers maximum melt temperatures between 3290 and 3490 K. Our results imply that natural lighting strikes may be an important agent of syn-eruptive morphological and chemical processing of volcanic ash.

19.
Vet Rec ; 161(24): 809-13, 2007 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-18083979

RESUMO

This study was designed to evaluate the efficacy of an inactivated vaccine based on a European-type strain of porcine reproductive and respiratory syndrome virus (PRRSV) against the reproductive form of the syndrome in breeding gilts, and any congenital disease in their piglets. Five gilts were vaccinated twice, following the manufacturer's instructions, before they were inseminated. Nine additional gilts remained unvaccinated and served as positive (five gilts) and negative (four gilts) controls. A European wild-type strain genetically divergent from the vaccine strain was used to challenge the five vaccinated and five unvaccinated positive control gilts at 90 days' gestation. The vaccination of the five seronegative gilts did not produce any clinical signs or adverse reactions. However, the vaccine failed to prevent the clinical signs associated with PRRSV infection, viraemia after the challenge and transplacental infection of their piglets. The reproductive performance of the vaccinated gilts was similar to that of the unvaccinated positive controls, and there were no statistically significant differences in most of the parameters tested. However, the preweaning mortality of the piglets born to the vaccinated gilts was significantly lower than that of the piglets born to the positive control gilts.


Assuntos
Transmissão Vertical de Doenças Infecciosas/veterinária , Síndrome Respiratória e Reprodutiva Suína/prevenção & controle , Vírus da Síndrome Respiratória e Reprodutiva Suína/imunologia , Complicações Infecciosas na Gravidez/veterinária , Vacinas Virais/imunologia , Animais , Animais Recém-Nascidos/virologia , Anticorpos Antivirais/sangue , Feminino , Feto/virologia , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Síndrome Respiratória e Reprodutiva Suína/patologia , Síndrome Respiratória e Reprodutiva Suína/transmissão , Gravidez , Complicações Infecciosas na Gravidez/patologia , Complicações Infecciosas na Gravidez/prevenção & controle , Resultado da Gravidez , Distribuição Aleatória , Suínos , Fatores de Tempo , Resultado do Tratamento , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologia , Vacinas Virais/administração & dosagem , Viremia/prevenção & controle , Viremia/veterinária
20.
Rev Sci Instrum ; 88(3): 034702, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28372400

RESUMO

This paper presents the principal considerations when designing DC-DC converters for space instruments, in particular for the power converter module as part of the first European space laser altimeter: "BepiColombo Laser Altimeter" on board the European Space Agency-Japan Aerospace Exploration Agency (JAXA) mission BepiColombo. The main factors which determine the design of the DC-DC modules in space applications are printed circuit board occupation, mass, DC-DC converter efficiency, and environmental-survivability constraints. Topics included in the appropriated DC-DC converter design flow are hereby described. The topology and technology for the primary and secondary stages, input filters, transformer design, and peripheral components are discussed. Component selection and design trade-offs are described. Grounding, load and line regulation, and secondary protection circuitry (under-voltage, over-voltage, and over-current) are then introduced. Lastly, test results and characterization of the final flight design are also presented. Testing of the inrush current, the regulated output start-up, and the switching function of the power supply indicate that these performances are fully compliant with the requirements.

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